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60
Learning 3D mesh segmentation and labeling
 ACM Trans. on Graphics
, 2010
"... head torso upper arm lower arm hand upper leg lower leg foot ear head torso arm leg tail body fin handle cup top base arm lens bridge antenna head thorax leg abdomen cup handle face hair neck fin stabilizer body wing top leg thumb index middle ring pinky palm big roller medium roller axle handle joi ..."
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Cited by 101 (7 self)
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head torso upper arm lower arm hand upper leg lower leg foot ear head torso arm leg tail body fin handle cup top base arm lens bridge antenna head thorax leg abdomen cup handle face hair neck fin stabilizer body wing top leg thumb index middle ring pinky palm big roller medium roller axle handle joint jaws head neck torso leg tail ear head torso back upper arm lower arm hand upper leg lower leg foot tail head wing body leg tail big cube small cube back middle seat leg head tentacle Figure 1: Labeling and segmentation results from applying our algorithm to one mesh each from every category in the Princeton Segmentation Benchmark [Chen et al. 2009]. For each result, the algorithm was trained on the other meshes in the same class, e.g., the human was labeled after training on the other meshes in the human class. This paper presents a datadriven approach to simultaneous segmentation and labeling of parts in 3D meshes. An objective function is formulated as a Conditional Random Field model, with terms assessing the consistency of faces with labels, and terms between labels of neighboring faces. The objective function is learned from a collection of labeled training meshes. The algorithm uses hundreds of geometric and contextual label features and learns different types of segmentations for different tasks, without requiring manual parameter tuning. Our algorithm achieves a significant improvement in results over the stateoftheart when evaluated on the Princeton Segmentation Benchmark, often producing segmentations and labelings comparable to those produced by humans. 1
Consistent Segmentation of 3D Models
 Computers 01/04/2010 81 K3D D1.4.1 & Graphics, IEEE SMI 2009 proceedings, (33)3
, 2009
"... This paper proposes a method to segment a set of models consistently. The method simultaneously segments models and creates correspondences between segments. First, a graph is constructed whose nodes represent the faces of every mesh, and whose edges connect adjacent faces within a mesh and correspo ..."
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Cited by 54 (5 self)
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This paper proposes a method to segment a set of models consistently. The method simultaneously segments models and creates correspondences between segments. First, a graph is constructed whose nodes represent the faces of every mesh, and whose edges connect adjacent faces within a mesh and corresponding faces in different meshes. Second, a consistent segmentation is created by clustering this graph, allowing for outlier segments that are not present in every mesh. The method is demonstrated for several classes of objects and used for two applications: symmetric segmentation and segmentation transfer. Key words: Mesh segmentation, Mesh analysis 1.
Joint shape segmentation with linear programming
 ACM Trans. on Graphics (Proc. SIGGRAPH Asia
, 2011
"... We present an approach to segmenting shapes in a heterogenous shape database. Our approach segments the shapes jointly, utilizing features from multiple shapes to improve the segmentation of each. The approach is entirely unsupervised and is based on an integer quadratic programming formulation of t ..."
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Cited by 43 (4 self)
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We present an approach to segmenting shapes in a heterogenous shape database. Our approach segments the shapes jointly, utilizing features from multiple shapes to improve the segmentation of each. The approach is entirely unsupervised and is based on an integer quadratic programming formulation of the joint segmentation problem. The program optimizes over possible segmentations of individual shapes as well as over possible correspondences between segments from multiple shapes. The integer quadratic program is solved via a linear programming relaxation, using a block coordinate descent procedure that makes the optimization feasible for large databases. We evaluate the presented approach on the Princeton segmentation benchmark and show that joint shape segmentation significantly outperforms singleshape segmentation techniques.
StyleContent Separation by Anisotropic Part Scales
"... We perform coanalysis of a set of manmade 3D objects to allow the creation of novel instances derived from the set. We analyze the objects at the part level and treat the anisotropic part scales as a shape style. The coanalysis then allows style transfer to synthesize new objects. The key to coa ..."
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Cited by 34 (21 self)
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We perform coanalysis of a set of manmade 3D objects to allow the creation of novel instances derived from the set. We analyze the objects at the part level and treat the anisotropic part scales as a shape style. The coanalysis then allows style transfer to synthesize new objects. The key to coanalysis is part correspondence, where a major challenge is the handling of large style variations and diverse geometric content in the shape set. We propose stylecontent separation as a means to address this challenge. Specifically, we define a correspondencefree style signature for style clustering. We show that confining analysis to within a style cluster facilitates tasks such as cosegmentation, content classification, and deformationdriven part correspondence. With part correspondence between each pair of shapes in the set, style transfer can be easily performed. We demonstrate our analysis and synthesis results on several sets of manmade objects with style and content variations.
Converting 3D Furniture Models to Fabricatable Parts and Connectors
"... generated by our algorithm. Right: We built a real cabinet based on the structure and dimensions of the generated parts/connectors. Although there is an abundance of 3D models available, most of them exist only in virtual simulation and are not immediately usable as physical objects in the real worl ..."
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Cited by 27 (2 self)
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generated by our algorithm. Right: We built a real cabinet based on the structure and dimensions of the generated parts/connectors. Although there is an abundance of 3D models available, most of them exist only in virtual simulation and are not immediately usable as physical objects in the real world. We solve the problem of taking as input a 3D model of a manmade object, and automatically generating the parts and connectors needed to build the corresponding physical object. We focus on furniture models, and we define formal grammars for IKEA cabinets and tables. We perform lexical analysis to identify the primitive parts of the 3D model. Structural analysis then gives structural information to these parts, and generates the connectors (i.e. nails, screws) needed to attach the parts together. We demonstrate our approach with arbitrary 3D models of cabinets and tables available online.
Symmetry Hierarchy of ManMade Objects
"... We introduce symmetry hierarchy of manmade objects, a highlevel structural representation of a 3D model providing a symmetryinduced, hierarchical organization of the model’s constituent parts. Given an input mesh, we segment it into primitive parts and build an initial graph which encodes interp ..."
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Cited by 21 (4 self)
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We introduce symmetry hierarchy of manmade objects, a highlevel structural representation of a 3D model providing a symmetryinduced, hierarchical organization of the model’s constituent parts. Given an input mesh, we segment it into primitive parts and build an initial graph which encodes interpart symmetries and connectivity relations, as well as selfsymmetries in individual parts. The symmetry hierarchy is constructed from the initial graph via recursive graph contraction which either groups parts by symmetry or assembles connected sets of parts. The order of graph contraction is dictated by a set of precedence rules designed primarily to respect the law of symmetry in perceptual grouping and the principle of compactness of representation. We show that symmetry hierarchy naturally implies a hierarchical segmentation that is more meaningful than those produced by local geometric considerations. We also develop an application of symmetry hierarchies for structural shape editing. 1.
Mesh decomposition with crossboundary brushes
 IN PROC. OF EUROGRAPHICS 2010) 29
, 2010
"... We present a new intuitive UI, which we call crossboundary brushes, for interactive mesh decomposition. The user roughly draws one or more strokes across a desired cut and our system automatically returns a best cut running through all the strokes. By the different natures of part components (i.e., ..."
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Cited by 12 (2 self)
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We present a new intuitive UI, which we call crossboundary brushes, for interactive mesh decomposition. The user roughly draws one or more strokes across a desired cut and our system automatically returns a best cut running through all the strokes. By the different natures of part components (i.e., semantic parts) and patch components (i.e., flatter surface patches) in general models, we design two corresponding brushes: partbrush and patchbrush. These two types of brushes share a common user interface, enabling easy switch between them. The partbrush executes a cut along an isoline of a harmonic field driven by the userspecified strokes. We show that the inherent smoothness of the harmonic field together with a carefully designed isoline selection scheme lead to segmentation results that are insensitive to noise, pose, tessellation and variation in user’s strokes. Our patchbrush uses a novel facetbased surface metric that alleviates sensitivity to noise and fine details common in regiongrowing algorithms. Extensive experimental results demonstrate that our cutting tools can produce userdesired segmentations for a wide variety of models even with single strokes. We also show that our tools outperform the stateofart interactive segmentation tools in terms of ease of use and segmentation quality.
MultiScale Partial Intrinsic Symmetry Detection
"... shown in uniform color. Note the detection of inter and intraobject symmetries, as well as cylindrical symmetry of the limbs. We present an algorithm for multiscale partial intrinsic symmetry detection over 2D and 3D shapes, where the scale of a symmetric region is defined by intrinsic distances ..."
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Cited by 10 (4 self)
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shown in uniform color. Note the detection of inter and intraobject symmetries, as well as cylindrical symmetry of the limbs. We present an algorithm for multiscale partial intrinsic symmetry detection over 2D and 3D shapes, where the scale of a symmetric region is defined by intrinsic distances between symmetric points over the region. To identify prominent symmetric regions which overlap and vary in form and scale, we decouple scale extraction and symmetry extraction by performing two levels of clustering. First, significant symmetry scales are identified by clustering sample point pairs from an input shape. Since different point pairs can share a common point, shape regions covered by points in different scale clusters can overlap. We introduce the symmetry scale matrix (SSM), where each entry estimates the likelihood two point pairs belong to symmetries at the same scale. The pairtopair symmetry affinity is computed based on a pair signature which encodes scales. We perform spectral clustering using the SSM to obtain the scale clusters. Then for all points belonging to the same scale cluster, we perform the secondlevel spectral clustering, based on a novel pointtopoint symmetry affinity measure, to extract partial symmetries at that scale. We demonstrate our algorithm on complex shapes possessing rich symmetries at multiple scales. Links: DL PDF WEB DATA 1
Fast approximate convex decomposition using relative concavity
, 2012
"... Approximate convex decomposition (ACD) is a technique that partitions an input object into approximately convex components. Decomposition into approximately convex pieces is both more efficient to compute than exact convex decomposition and can also generate a more manageable number of components. I ..."
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Cited by 7 (1 self)
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Approximate convex decomposition (ACD) is a technique that partitions an input object into approximately convex components. Decomposition into approximately convex pieces is both more efficient to compute than exact convex decomposition and can also generate a more manageable number of components. It can be used as a basis of divideandconquer algorithms for applications such as collision detection, skeleton extraction and mesh generation. In this paper, we propose a new method called Fast Approximate Convex Decomposition (FACD) that improves the quality of the decomposition and reduces the cost of computing it for both 2D and 3D models. In particular, we propose a new strategy for evaluating potential cuts that aims to reduce the relative concavity, rather than absolute concavity. As shown in our results, this leads to more natural and smaller decompositions that include components for small but important features such as toes or fingers while not decomposing larger components, such as the torso, that may have concavities due to surface texture. Second, instead of decomposing a component into two pieces at each step, as in the original ACD, we propose a new strategy that uses a dynamic programming approach to select a set of nc noncrossing (independent) cuts that can be simultaneously applied to decompose the component into nc +1 components. This reduces the depth of recursion and, together with a more efficient method for computing the concavity measure, leads to significant gains in efficiency. We provide comparitive results for 2D and 3D models illustrating the improvements obtained by FACD over ACD and we compare with the segmentation methods in the Princeton Shape Benchmark [5]. 1.
GUIBAS L.: Discovery of intrinsic primitives on triangle meshes
 Comp. Graph. Forum
"... Figure 1: Localized vector fields which are an optimized linear combination of approximate Killing fields (left), a segmentation from these fields (middle), and a decomposition into intrinsic primitives with prominent intrinsic symmetry generators (right). The discovery of meaningful parts of a shap ..."
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Cited by 7 (1 self)
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Figure 1: Localized vector fields which are an optimized linear combination of approximate Killing fields (left), a segmentation from these fields (middle), and a decomposition into intrinsic primitives with prominent intrinsic symmetry generators (right). The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almostisometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recentlydeveloped method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to stateoftheart methods using the Princeton Segmentation Benchmark.